#ifndef __PROCESS_POOL_HPP__
#define __PROCESS_POOL_HPP__

#include <iostream>
#include <vector>
#include <cstdlib>
#include <unistd.h>
#include <sys/wait.h>
#include "Task.hpp"


// 先描述
class Channel
{
public:
    Channel(int fd, pid_t id)
        :_wfd(fd)
        ,_subid(id)
    {
        _name = "channel-" + std::to_string(_wfd) + "-" + std::to_string(_subid);
    }

    ~Channel()
    {}

    void Send(int code)
    {
        int n = write(_wfd, &code, sizeof(code));
        (void)n;
    }

    void Close()
    {
        close(_wfd);
    }
    void Wait()
    {
        pid_t rid = waitpid(_subid, nullptr, 0);
        (void)rid;
    }

    int Fd() { return _wfd; }
    pid_t SubId() { return _subid; }
    std::string Name() { return _name; }

private:
    int _wfd;
    pid_t _subid;
    std::string _name;
};

// 再组织
class ChannelManger
{
public:
    ChannelManger()
        :_next(0)
    {}

    void Insert(int wfd, pid_t subid)
    {
        _channels.emplace_back(wfd, subid);
        // Channel c(wfd, subid);
        // _channels.push_back(std::move(c));
    }

    void PrintChannel()
    {
        for (auto &channel : _channels)
        {
            std::cout << channel.Name() << std::endl;
        }

    }

    Channel &Select()
    {
        auto &c = _channels[_next++];
        _next %=_channels.size();
        return c;
    }

    void CloseAll()
    {
        for (auto &channel : _channels)
        {
            channel.Close();
            //std::cout << "关闭: " << channel.Name() << std::endl;
        }
    }

    void StopSubProcess()
    {
        for (auto &channel : _channels)
        {
            channel.Close();
            std::cout << "关闭: " << channel.Name() << std::endl;
        }
    }
    void WaitSubProcess()
    {
        for (auto &channel : _channels)
        {
            channel.Wait();
            std::cout << "回收: " << channel.Name() << std::endl;
        }
    }
    
    void CloseAndWait()
    {
        for (auto &channel : _channels)
        {
            channel.Close();
            std::cout << "关闭: " << channel.Name() << std::endl;
            channel.Wait();
            std::cout << "回收: " << channel.Name() << std::endl;
        }

        // 方案1：倒着关
        // for (int i = _channels.size()-1; i >= 0; i--)
        // {
        //     _channels[i].Close();
        //     std::cout << "关闭: " <<  _channels[i].Name() << std::endl;
        //      _channels[i].Wait();
        //     std::cout << "回收: " <<  _channels[i].Name() << std::endl;
        // }

    }

    ~ChannelManger()
    {}

private:
    std::vector<Channel> _channels;
    int _next;
};


const int gdefaultnum = 5;//固定5个子进程

class ProcessPool
{
public:
    ProcessPool(int num)
        :_process_num(num)
    {
        _tm.Register(PrintLog);
        _tm.Register(DownLoad);
        _tm.Register(Upload);
    }

    void Work(int rfd)
    {
        while (true)
        {
            int code = 0;
            ssize_t n = read(rfd, &code, sizeof(code));
            if (n > 0)
            {
                if (n != sizeof(code))
                {
                    continue;
                }
                std::cout << "子进程[" << getpid() << "]收到一个任务码: " << code << std::endl;
                _tm.Execute(code);
            }
            else if (n == 0)
            {
                std::cout << "子进程退出~" << std::endl;
                break;
            }
            else
            {
                std::cout << "读取错误~" << std::endl;
                break;
            }
        }
        
        // while(true)
        // {
        //     std::cout << "我是子进程,我的rfd是: " << rfd << std::endl;
        //     sleep(5);
        // }
    }

    bool Start()
    {
        for (int i = 0; i < _process_num; i++)
        {
            // 1. 创建管道
            int pipefd[2] = {0};
            int n = pipe(pipefd);
            if (n < 0) 
                return false;
            // 2. 创建子进程
            pid_t subid = fork();
            if (subid < 0)
                return false;
            else if (subid == 0) // 子进程 读
            {
                sleep(1);
                // 子进程关闭继承下来的，哥哥进程的写端
                std::cout << "####################################" << "第" << i << "次" << std::endl;
                _cm.PrintChannel();
                std::cout << "####################################" << std::endl;
                _cm.CloseAll();
                // 3. 关闭不要的文件
                close(pipefd[1]);
                Work(pipefd[0]); // 测试读端
                close(pipefd[0]);
                exit(0);

            }
            else // 父进程 写
            {
                sleep(1);
                // 3. 关闭不要的文件
                close(pipefd[0]);
                _cm.Insert(pipefd[1], subid);
            }
        }
        return true;
    }

    void Debug()
    {
        _cm.PrintChannel();
    }

    void Run()
    {
        // 1. 选择一个任务
        int taskcode = _tm.Code();

        // 2. 选择一个信道子进程，负载均衡的选择一个子进程，完成任务
        auto &c = _cm.Select();
        std::cout << "选择了一个子进程: " << c.Name() << std::endl;

        // 3. 发送任务
        c.Send(taskcode);
        std::cout << "发送了一个任务码: " << taskcode << std::endl;
    }

    void Stop()
    {
        // 关闭父进程的所有fd
        //_cm.StopSubProcess();
        // 回收所有子进程
        //_cm.WaitSubProcess();

        _cm.CloseAndWait();
    }

    ~ProcessPool()
    {}

private:
    ChannelManger _cm;
    int _process_num;
    TaskManager _tm;
};



#endif